111 lines
3.9 KiB
Python
111 lines
3.9 KiB
Python
from __future__ import annotations
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import unittest
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from app.simulation.core.peng_robinson import AIR_PR, HELIUM_PR, NITROGEN_PR, PengRobinsonFluid
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class PengRobinsonTest(unittest.TestCase):
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def test_helium_near_ideal_at_atmospheric_condition(self) -> None:
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z = HELIUM_PR.compressibility_factor(101_325.0, 300.0)
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density = HELIUM_PR.density(101_325.0, 300.0)
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self.assertAlmostEqual(z, 1.0, delta=1.0e-3)
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self.assertAlmostEqual(density, 0.1625, delta=0.002)
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def test_helium_density_pressure_round_trip(self) -> None:
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pressure = 15.3e6
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temperature = 293.15
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density = HELIUM_PR.density(pressure, temperature)
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self.assertGreater(HELIUM_PR.compressibility_factor(pressure, temperature), 1.0)
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self.assertAlmostEqual(
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density,
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24.114225444477153,
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delta=1.0e-12,
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)
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self.assertAlmostEqual(
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HELIUM_PR.pressure_from_density(temperature, density),
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pressure,
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delta=pressure * 1.0e-12,
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)
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def test_helium_residual_enthalpy_is_small_at_atmosphere(self) -> None:
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self.assertAlmostEqual(
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HELIUM_PR.residual_specific_enthalpy(101_300.0, 298.15),
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25.3556466754,
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delta=0.01,
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)
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def test_helium_residual_enthalpy_captures_high_pressure_departure(self) -> None:
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self.assertAlmostEqual(
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HELIUM_PR.residual_specific_enthalpy(13_839_965.0, 287.7322),
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12788.0457342,
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delta=0.1,
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)
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def test_residual_isochoric_heat_capacity_is_internal_energy_derivative(
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self,
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) -> None:
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temperature = 292.3997890954483
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density = 24.02697515640726
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temperature_step = 1.0e-3
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numerical_derivative = (
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HELIUM_PR.residual_specific_internal_energy_at_density(
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temperature + temperature_step,
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density,
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)
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- HELIUM_PR.residual_specific_internal_energy_at_density(
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temperature - temperature_step,
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density,
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)
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) / (2.0 * temperature_step)
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self.assertAlmostEqual(
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HELIUM_PR.residual_isochoric_heat_capacity_at_density(
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temperature,
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density,
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),
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numerical_derivative,
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delta=1.0e-6,
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)
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def test_air_reference_remains_available_for_other_models(self) -> None:
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z = AIR_PR.compressibility_factor(101_325.0, 300.0)
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density = AIR_PR.density(101_325.0, 300.0)
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self.assertAlmostEqual(z, 1.0, delta=1.0e-3)
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self.assertAlmostEqual(density, 1.177, delta=0.01)
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def test_nitrogen_can_return_multiple_roots(self) -> None:
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roots = NITROGEN_PR.compressibility_roots(1.0e6, 100.0)
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self.assertEqual(len(roots), 3)
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self.assertLess(roots[0], roots[-1])
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self.assertEqual(NITROGEN_PR.compressibility_factor(1.0e6, 100.0, phase="liquid"), roots[0])
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self.assertEqual(NITROGEN_PR.compressibility_factor(1.0e6, 100.0, phase="vapor"), roots[-1])
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def test_custom_fluid_can_be_defined_explicitly(self) -> None:
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fluid = PengRobinsonFluid(
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name="custom_helium",
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molar_mass=0.004002602,
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critical_temperature=5.1953,
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critical_pressure=227_460.0,
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acentric_factor=-0.382,
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)
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self.assertAlmostEqual(fluid.specific_gas_constant, 2077.3, delta=0.5)
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self.assertAlmostEqual(fluid.compressibility_factor(1.0e6, 298.15), HELIUM_PR.compressibility_factor(1.0e6, 298.15))
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def test_rejects_invalid_states(self) -> None:
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with self.assertRaises(ValueError):
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HELIUM_PR.compressibility_factor(0.0, 300.0)
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with self.assertRaises(ValueError):
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HELIUM_PR.density(101_325.0, 0.0)
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with self.assertRaises(ValueError):
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HELIUM_PR.pressure_from_density(300.0, -1.0)
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if __name__ == "__main__":
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unittest.main()
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